Controlling particle textures
If it's cycles you are using it might be possible. All of the particles do have a unique ID that you maybe can use to give them different textures. The ID is used to calculate ag. collisions, if i haven't misunderstand how it works. 
In the math node should it be an options for compare values, if you set it to check if the value is the same and if they are it will send 1. 
You should be able to do it but I'm not sure if it is worth the extra time.